test: use env in shebang of system tests

This should allow the tests to run on systems where bash is not in /bin.

test/system/001-minimal

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/002-extended

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/003-memlock

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/004-priority

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/005-scfilter

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/006-privdrop

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/007-cmdmon

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/100-clockupdate

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/101-rtc

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/102-hwtimestamp

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/103-refclock

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 . ./test.common
 

test/system/104-systemdirs

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 TEST_LIBDIR=${CHRONY_LIBDIR:-/var/lib/chrony}
 TEST_LOGDIR=${CHRONY_LOGDIR:-/var/log/chrony}

test/system/run

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 print_help() {
 	echo "$1 [-a] [-d] [TEST]..."

test/system/test.common

@@ -38,7 +38,7 @@ test_start() {
 	if [ "$user" != "root" ]; then
 		id -u "$user" > /dev/null 2> /dev/null || test_skip "missing user $user"
 		chown "$user:$(id -g "$user")" "$TEST_DIR" || test_skip "could not chown $TEST_DIR"
-		su "$user" -s /bin/bash -c "touch $TEST_DIR/test" 2> /dev/null || \
+		su "$user" -s /bin/sh -c "touch $TEST_DIR/test" 2> /dev/null || \
 			test_skip "$user cannot access $TEST_DIR"
 		rm "$TEST_DIR/test"
 	fi